Objectives (1) To evaluate long-term patterns of female productivity and reproductive failure in large socially housed populations of rhesus macaques and stumptailed macaques; (2) to assess results in relation to female genetic relationships, social rank, and -- in future, paternity; (3) to document age-related changes in reproductive outcome for female macaques and patterns of reproductive senescence. ABSTRACT:In large social groups of macaques in biomedical facilities or breeding centers, there is often a desire for maximal productivity but without an intensive-management approach. Better understanding of the social and genetic influences on patterns of female reproductive success and failure is of practical importance in colony management, is relevant to models of human reproductive health, and is of theoretical importance. The large groups of rhesus and stumptailed macaques housed in comparable conditions at the Vilas Facility for Ethological Research and Breeding represent an invaluable resource for research in this area Individual reproductive histories (including stillbirths and spontaneous abortions) are documented for each female in two large groups of rhesus macaques and one large group of stumptailed macaques for up to 20 years. This study places a particular focus on the period since 1984 for analysis of reproductive failure and for inter-species comparison, due to historical factors. The body of data allows evaluation of reproductive success approaching life-span data for many females, and will include many others in the next five-year plan. Data on female matriline membership, number of generations from founder stock, social rank, and position within the matriline, are being evaluated in association with data on productivity. Differential reproductive performance of females within families will be evaluated for possible evidence of reproductive suppression. In future, it will be possible to evaluate paternity on a routine basis, and therefore to identify possible patterns in paternal genetic contribution in cases of reproductive failure. Normative patterns of reproduction and life-span productivity will be analyzed comparatively to better understand the evolutionary adaptations of the two species to qualitatively different reproductive strategies. Key Words life-span productivity, social and genetic influences on reproduction, Macaca